1. Field of the Disclosure
Embodiments disclosed herein generally relate to systems and methods usable to separate various constituents of fluids produced from a formation. Specific embodiments are directed to a versatile, all-in-one process skid usable to receive or extract energy from a producing formation, such as flowback from a fracturing recovery process. The skid may be provided with monitoring (e.g., remote monitoring) and control capabilities to evaluate real time process performance, and in various embodiments, to enable unmanned operation of the system. In particular embodiments, the skid may include a first inlet separator, a line heater with high-pressure coils, a 2-phase separator, and/or a 3-phase separator, as well as other monitoring devices.
2. Background
Various formation stimulation techniques, and in particular, fracturing techniques, have increased in use as the economic incentive to recover hydrocarbons and other fluids from marginally producing formations has grown. One estimate shows that 90% of natural gas wells in the United States use a fracturing process to produce gas at economically affordable rates. Fracturing operations are usable to overcome deficiencies in the recovery process that result from limited formation permeability, which prevents formation fluids from being readily and easily produced. As exploration for hydrocarbons within unconventional shale plays and other sources that generally require fracturing operations increases, the pressure and volume of fracturing fluid used during typical operations has risen sharply.
Referring to FIG. 1, conventional fracturing techniques 100 typically involve injection of a high-pressure fracturing fluid from a source 101 into a formation 107, such that the fracturing fluid initiates and propagates a fracture 180 in the formation that increases formation permeability and improves the flow path for formation fluids. Highly permeable proppant materials entrained in the fracturing fluid maintain the fracture, e.g., “propping” the fracture open, so that an increase in recovery of hydrocarbons may be achieved. Proppant materials can include, for example, sand, ceramic beads, glass beads, etc.
In a single well fracturing process, thousands or even hundreds of thousands of pounds of proppant material can be used, as well four million gallons of water, or more. As such, there is a significant consumption of materials and a significant generation of waste that occurs as a result of a fracturing process. During a more intensive fracturing operation, e.g., to produce from an unconventional shale play, an even larger quantity of proppant, water, and other materials can be used.
Accordingly, a final step of a fracturing process, can include the recovery of the injected fluids, which occurs by flowing or lifting the well (e.g., energy recovery), also referred to as “flowback” FL. When the flowback recovery process 190 begins, at least a portion of the injected fracturing fluid or flowback FL is produced from the formation 107 and processed by a flowback processing system 102. The flowback stream generally contains an oil/water mixture, along with a variety of other contaminants carried therein. The contaminants may include, for example, other hydrocarbons, such as C1-C6 light hydrocarbons, C20 and greater hydrocarbons, gelling additives, as well as other contaminants, including organometals and the like, in addition to proppant materials.
Raw materials consumed during fracturing processes, such as water, are extremely valuable resources that must often be conserved where possible due to various laws or regulations. For example, water used to make fracturing fluid may be available from local streams and ponds, or purchased from a municipal water utility; however, the use of such water can be extremely expensive due to the permits required. Alternatively, tanker trucks can be used to transport water to a well site; however, due to the fact that many oil and gas fields are in remote locations, transportation of water to a well site, along with proppant material and other required materials and/or equipment, can be prohibitively expensive.
One method to conserve materials consumed by fracturing operations includes separation, cleaning, and recycling of the flowback fluid. On-site processing equipment used at a well location is the most common means by which materials are recycled. There is also interest in the industry for recycling and/or separating hydrocarbons from the flowback stream, such as through removal of the contaminants therein. Doing so requires additional separation of the proppant materials and other contaminants from the flowback stream.
In addition to the large quantity of materials consumed by a fracturing operation, the substantial amount of waste generated can be problematic. Previously, recovered waste streams were simply buried underground. However, due to increased public and regulatory scrutiny and pressure, the oil and gas industry has sought to conduct fracturing processes in a manner that is as environmentally benign as possible. Concerns about pollution leaching into the soil and affecting ground water sources have stimulated state and federal legislation that effectively eliminates the ability to bury waste streams. Thus, flowback streams are generally categorized as hazardous waste materials, and must be treated accordingly.
Conventional practices include the use of storage containers to store flowback materials, and the use of tanker trucks to transport the stored materials away from a well site for treatment. For a single well, these practices can require 300 tanker trucks, or more, to carry more than two million gallons of flowback materials for offsite disposal. In addition to transport costs, these trucks and/or storage containers are prone to failure and spilling while in transit, which results in toxic spills and costly environmental hazards. Additionally, the time required to properly interconnect all of the trucks can be inefficient. Due to the rig-up time required, a single fracturing operation may require longer than 45 days to complete.
On-site separation operations typically require “trains” of trucks. The large number of trucks used to provide separation operations, as well as the additional trucks required to support such operations (e.g., to transport waste and/or water), creates significant expense and overhead to when performing fracturing processes. However, these “trains” do not provide means to separate a three-component system of oil, water and sand (or similar proppant material and/or contaminants) into cleansed and recyclable constituent parts. Furthermore, these processes are not self-contained within a single mobile unit, nor do they have control and monitor systems associated therewith that can enable on-site, remote, or even unmanned operation thereof.
Therefore, there continues to be a need for a mobile, all in one, process unit and system capable of providing flowback recovery separation and recycling at a distant and remote location. There is a further need for a flowback recovery process that maximizes the recovery of saleable oil and gas during the recovery phase of a fracturing process. There is also a need for a versatile, all in one, process skid usable to receive or extract energy from a producing formation that is configured to substantially reduce and/or improve the recovery process.
There are additional needs for a system that includes a single mobile unit to separate flowback streams that also reduces rig up time, is operationally autonomous (e.g., able to operate unmanned), and improves overall system safety.